Field of the Disclosure
The present disclosure relates generally to water treatment. In particular, but not by way of limitation, the present disclosure is related to treatment of wastewater having high total dissolved solids.
Description of Related Art
The presence of silica in feed waters greatly complicates and increases the costs of operating many systems used for energy recovery and industrial water and wastewater treatment.
Silica forms intractable scale deposits on heat transfer surfaces and other surfaces or membranes where aqueous streams containing silica are concentrated. Most notably, reduced performance and failure of boilers, steam generators, turbines, evaporators, cooling towers, and reverse osmosis treatment systems are attributed to formation of intractable silica scale. Replacement of silica fouled equipment is often less costly than efforts to clean or remove the offending silica scale.
One theoretical method for silica removal is via adsorption on activated alumina in a fixed bed system. However, those of skill in the art are well aware that since activated alumina is a surface-oriented process, very little silica can be loaded onto each alumina particle, and hence vast volumes of alumina would be required in the fixed bed in order to implement any commercial silica treatment solution. As such, this approach has not been pursued by those of skill in the art.
Instead, various methods have been used to treat silica-laden liquids, each having their own drawbacks. For instance, the most common treatments are demineralization, hot lime softening, magnesium addition and coagulation, and sodium aluminate coagulation. Each of these treatments are complex, expensive, and generate large quantities of intractable by-product wastes.
Furthermore, although ion exchange processes can be used to remove ionic species, in most target water streams, which have a near-neutral pH, silica is present as non-ionic species and thus not amendable to ion-exchange treatment.